The oyster mushroom is a delicious tradition in Japan, Korea and China. Not only are they valued for its taste, but also for its healthy qualities. Its flavour is exquisite and the amount of calories contained in 100g of fresh mushrooms is 27 calories. Less than those contained in two teaspoonfuls of sugar (36cal).  According to recent reports, these mushrooms have nearly twice the volume of fibre of typical champignons. They are considered an essential part  of the daily diet on account of their nutritional contribution to the body, such as the amino acids they provide. Adding oyster mushrooms to your menus will give an special taste any of your dishes: soup, sauce, stew, roasted meat…they are delicious!

Nutritional values

Mushrooms have an important nutritional value. They have moderate quantities of high-quality protein with all the essential amino-acids, mainly alanine, glutamic acid and glutamine. They are an important source of minerals (potassium, iron, phosphorus, calcium) and vitamins B1 (thiamin), B2 (riboflavin), B3 (niacin) and D. They have high contents (36 to 58mg/100g dry weight) of ascorbic acid (vitamin C) so that they can be a very good source of antioxidants and reducing agents.
Mushrooms contain a significant quantity of carbohydrates (pentose, hexose, saccharose, sugar alcohol, acid-sugar, methyl-pentose) which are not the starches type (make one get fat). Their dietary fiber content is also high, specially quitine, a polysaccharide with exceptional properties as it absorbs the fat easily in the digestive tract.
The lipids fraction in this type of mushrooms is not significant because of their small quantity. It must be mentioned that fatty acids are predominantly unsaturated, easily digested and hypolipidemic.

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Medicinal Properties:

Mushrooms fall into the category of prebiotic food: they help the body to fight illnesses, to restore the well-being and the body natural equilibrium (homeostasis). They regulate the immune system eliminating external agents that could unbalance our health. The frequent consumption of some types of mushrooms might help in the prevention of illnesses which are commonly caused by inadequate diets.

Anti-tumour effects
Some edible mushrooms, such as Pleurotus ostreatus, contain high quantities of complex molecular structure polysaccharides. They have been found to have an important anti-tumour capacity. It has been proved by laboratory testing that these substances are able to delay and decrease the size of some types of tumors, apart from preventing their formation. It is likely that the mechanism consists in that these polysaccharides act as potentiators of the defense cells which destroy cancer cells.

Antiviral effects
The same mechanisms that stimulate the immune system in the body act in order to fight some infectious agents, both viral and bacterial ones. The fact that certain defense systems could be activated by these polysaccharides may contribute as adyuvant in immune deficiency illnesses such as AIDS, and other autoimmune diseases as rheumatoid arthritis or lupus erythematosus.
It has been found that the mycelium of Pleurotus contains a mixture of different
low molecular weight polysaccharides and substances similar to zeatin which contain cytokinin. It is known they have antiviral effects and they cause neither side effects nor toxicity in sick patients.
The glutamic acid is an amino-acid which has a stimulating effect on the immune system and it is present in high concentrations in mushrooms.
Other important substances with antibiotic properties are the volatile aromatic compounds that characterize most Pleurotus species. These are molecules responsible for the fragrance and characteristic flavor that distinguishes this type of mushrooms. These substances have shown to have a strong antibacterial capacity.

Cholesterol Control
It has been proved at experimental level that the frequent consumption of mushrooms lowers the level of fatty acids in blood and cholesterol in the liver. An increase in the phospholipids cholesterol relationship was also found suggesting a favorable anti-atherogenic effect. Therefore, it may help to prevent the hardening of arteries and as a consequence the prevention of possible cardiovascular illnesses.
On the other hand, it has been found that in the fruit bodies of Pleurotus ostreatus there is a natural substance that lowers cholesterol, triglycerides and very low density lipoproteins in blood called lovastatin. It is used as an active principle of different medicines commonly prescribed by physicians for hypercholesterolemia treatment. Besides, mushrooms also contain Mevinolin and other related substances which are powerful inhibitors of HMG CoA
reductase, main enzyme responsible for cholesterol biosynthesis

Anti-inflammatory effect
Mushrooms also have anti-inflammatory properties. Some research has been carried out: glycopeptides (lectins) containing amino-acids have been isolated from glucose, arabinose, galactose, mannose, and xylose, in the carbohydrates chain, showing an excellent fungicide and antibiotic capacity.

Hepatoprotective effect
Laboratory experiments have shown that mushroom consumption lowers cholesterol and triglycerides levels. At histological level, it has been found that liver steatosis is less when consuming mushrooms. Thus, it can also be mentioned their hepatoprotective effect.
Anti-hypertension effects
Lowering cholesterol in blood by itself tends to cause blood pressure to diminish. It is also known that a potassium-rich diet can help to decrease arterial hypertension. Almost all edible mushrooms are rich in this mineral. It has also been demonstrated that the consumption of mushrooms allows a better absorption of minerals at intestinal level due to the presence of metaloproteins.

Antioxidant effect